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In the recent years, it comes into more notice for Vehicular Ad-hoc Network (VANET) due to good applications of VANET. For example, those applications include the driving secure and some serviced applications (e.g., loading electric maps, web Service, and so on). The delivered message about driving secure is called the traffic messages, and the delivered message about serviced applications is called the routine message. The traffic message is more important than the routine message. When vehicle is driven on the road and the events are happened (example of accident, or jam), it can broadcast these happened events to notify others on the same road by VANET and let others to earlier get the awareness to avoid the more serious accident or traffic jam. In fact, these traffic messages are related to the life of driver and passengers. Thus, we must pay attention to the correctness of these traffic messages when these messages are sent in VANET, i.e., it will result the serious traffic disorder if these messages are altered or forged by illegal offenders and we don¡¦t permit this situation to occur. Hence, the network security in VANET is the emphasis in this paper. There are some studies that have proposed some scheme for message authentication in VANET. However, there still exist some imperfections in these schemes (for example, the communication overhead is too heavy). Thus, this thesis proposes two schemes to improve these drawbacks based on some schemes which had been proposed. The first proposed scheme verifies message with the RSU¡¦s aid in the RSU scenario. The second proposed scheme uses the clustering to work a rotation for verifying message for no RSU scenario. The two schemes can efficiently reduce the communication overhead to form an integrity message authentication system.

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As the rapid evolution of the technology and the network communication, people can share the multimedia content more easily through the Internet. And devices for accessing the Internet include not only the desktop computers but also cell phones, PDAs, and computers on the vehicles. Vehicular ad-hoc networks, which allow mobile users to access the Internet with the computers on cars is one of the most promising technology in the near future. Through VANET, vehicles can not only share the traffic information to avoid accidents, but also exchange the multimedia content through the peer to peer sharing technology. In this thesis we propose using the network coding technology to encode/decode the file blocks in VANET, clustering the vehicles according to their mobility, and combining the ROMSGP and modifying the priority method of the VANETCODE scheme in order to enhance the overall performance of VANETs.

Stuttgart, Univ., Diss., 2007.

The paper introduces a Vehicular Network Integrated Simulator (VNetIntSim) that integrates transportation modelling with Vehicular Ad Hoc Network (VANET) modelling. Specifically, VNetIntSim integrates the OPNET software, a communication network simulator, and the INTEGRATION software, a microscopic traffic simulation software. The INTEGRATION software simulates the movement of travellers and vehicles, while the OPNET software models the data exchange through the communication system. Information is exchanged between the two simulators as needed. As a proof of concept, the VNetIntSim is used to quantify the impact of mobility parameters (traffic stream speed and density) on the communication system performance, and more specifically on the data routing (packet drops and route discovery time).

在車載隨意網路中，由於道路環境的多樣性，使得如何解決資料封包繞徑問題成為相關領域中的一項挑戰。雖然各種新的方法相繼被提出，然而對於在不同環境中如何選擇最佳方法的相關問題，卻缺乏較廣泛的研究及實證。有鑑於此，有別於單一改良型的繞徑方法，我們提出一個整合式的架構來解決面對不同環境時的繞徑問題，以整合多重繞徑方法於單一系統中。我們並以跨層式方法設計繞徑模組的選用模式，再配合廣播封包整合的機制等三種策略方法，讓車輛在不同的道路環境下，能在多個繞徑方法提供的路徑當中，選擇最佳的路徑來傳遞封包，並藉由取得其他網路階層的相關資訊，作為最佳化選擇的依據。同時，封包若在傳遞過程中，原來的路徑發生中斷時，系統能改以其他繞徑方法繼續傳遞封包至目的節點，減少來源端封包重傳的需求。最後為了減輕因數個繞徑方法同時進行所可能產生的廣播風暴問題，我們以封包列車的方式來整合廣播封包。從模擬實驗結果證明，本系統能在不同的道路車輛環境及車輛分布密度，提升資料的傳輸率，克服因節點位置快速變動而導致傳輸率下降的問題。 / Design of data routing between vehicle and vehicle (V2V) is a critical issue for VANET due to dynamics of traffic road environment. Therefore, there are some proposed solutions to cope with such problem in the past years. It is difficult, however, to choose a best approach from those solutions for a car node that could communicate by wireless under all kinds of rigid environment. In this paper, instead of designing new routing method, we proposed an architecture to cope with the problem. We use three building blocks to construct our methodology: combination of multiple routing protocols, path selection by cross-layer design and integration of broadcast routing packets. A car node may find more paths provided by the multiple routing modules for delivering packets to the destination. By using cross-layer design we demonstrate how to determine one from the routing modules that can provide the best path for packet according to information collected from the other network layers. Besides, a recovery of forwarding can be performed by this architecture while a broken path occurs during the packet delivering. Finally, we proposed a packet train idea to solve the broadcast storm which could be incurred by the multiple routing protocols operating at the same time. The experiment results show that our proposed architecture can raise the data throughput under different mobility environments of VANET.

Vehicular ad hoc networks (VANET) is a class of ad hoc networks build to ensure the safety of traffic. This is important because accidents claim many lives. Trust and security remain a major concern in VANET since a simple mistake can have catastrophic consequence. A crucial point in VANET is how to trust the information transmitted when the neighboring vehicles are rapidly changing and moving in and out of range. Current reputation systems for VANET try to establish trust between entities, which might not be required for practical scenarios. Due to the ephemeral nature of VANET, reputation schemes for mobile ad hoc networks (MANETs) cannot be applied to VANET. In this thesis, we point out several limitations of reputation trust management schemes for VANET. In particular, we identify the problem of information cascading and oversampling, which commonly arise in social networks. Oversampling is a situation in which a node observing two or more nodes, takes into consideration both their opinions equally without knowing that they might have influenced each other in decision making. We show that simple voting for decision making, leads to oversampling. We propose a solution to overcome this problem in VANET. We also suggest new ways to merge reputation schemes with misbehavior detection schemes to establish a trustworthy VANET.

Vehicular ad hoc network (VANET) is an emerging new communication technol-ogy which has attracted a lot of research attention from academic community and indus-try. For many applications in VANETs, information has to be transmitted through mul-tiple hops before it reaches its destination that makes it a subject to various security at-tacks and privacy breaches. Thus, security and privacy issues could limit its adaption by the public community. In this study, we propose and evaluate social based trustworthy data forwarding scheme for VANET. First, by using social network analysis techniques, we provide a framework to strategically deploy Road-Side Units (RSUs) infrastructure in order to im-prove reliability, efficiency, and high packet delivery for VANET. It is based on multiple social centrality assessments of street network which help in placing RSUs at high social intersections. This social placement of RSUs will dramatically improve data dissemina-tion as the opportunity of contacting vehicles increase while costs of RSU deployment can be kept under control. Second, we propose a secure and privacy-preserving message forwarding protocol, which utilizes RSUs to forward messages between vehicles. The protocol takes advantage of high performance capability of RSUs to store and forward messages to their destinations, where these RSUs utilize re-encryption technique to form a mix network to provide adequate privacy for senders and receivers. Then detailed anal-ysis in terms of security, message overhead, delivery ratio, and average delay are per-formed to evaluate the efficiency and effectiveness of our proposed scheme. Lastly, we tackled the security and privacy challenges existing in social-aware data diffusion by proposing an efficient vehicle social evaluation (EVSE) scheme. Our scheme enables each vehicle to show its authentic social evaluation to others while not disclosing its past location information. As a result, it can meet the prerequisites for the success of social aware data diffusion in VANETs. / UOIT

Vehicular ad hoc networks (VANET) is a class of ad hoc networks build to ensure the safety of traffic. This is important because accidents claim many lives. Trust and security remain a major concern in VANET since a simple mistake can have catastrophic consequence. A crucial point in VANET is how to trust the information transmitted when the neighboring vehicles are rapidly changing and moving in and out of range. Current reputation systems for VANET try to establish trust between entities, which might not be required for practical scenarios. Due to the ephemeral nature of VANET, reputation schemes for mobile ad hoc networks (MANETs) cannot be applied to VANET. In this thesis, we point out several limitations of reputation trust management schemes for VANET. In particular, we identify the problem of information cascading and oversampling, which commonly arise in social networks. Oversampling is a situation in which a node observing two or more nodes, takes into consideration both their opinions equally without knowing that they might have influenced each other in decision making. We show that simple voting for decision making, leads to oversampling. We propose a solution to overcome this problem in VANET. We also suggest new ways to merge reputation schemes with misbehavior detection schemes to establish a trustworthy VANET.